The singledispatch library brings functools.singledispatch from Python
3.4 to Python 2.6-3.3.

PEP 443 proposed to expose a mechanism in the functools standard library
module in Python 3.4 that provides a simple form of generic programming
known as single-dispatch generic functions.

This library is a backport of this functionality to Python 2.6 - 3.3.
